This invention relates to a method of casting chocolate, cream, and the like products, and to a forming machine and bottom plate for implementing the method.
As is known, for casting chocolate, cream, candy, and the like products with either of the two most commonly used methods, i.e. spot and continuous casting, it has been heretofore possible to employ forming machines of two types, namely reciprocating piston and rotary piston forming machines.
Irresprective of its design, each forming machine is provided with an equal number of chocolate delivery holes to the number of reciprocating or rotary pistons it comprises. In order to be able to use one forming machine with different master molds, i.e. molds having either a different number of receptacles or the same number of differently patterened receptacles, or again, to produce different chocolate articles with one master mold, it is known to associate with the bottom delivery end of the forming machine distributor bottom plates having inlet holes which correspond by number and arrangement to the forming machine delivery holes. Also known is to arrange said holes of the bottom plates in a branched pattern such that a greater number of mold receptacles can be filled with respect to the forming machine delivery holes, and accordingly, the product can be distributed more evenly to the mold receptacles, especially where large surface receptacles are used, as for bars and the like. In each case, those pistons which happen to be in communication with forming machine delivery holes not controlled to deliver chocolate for the time being, must be stopped or somehow prevented from delivering chocolate while the machine is in operation.
Thus, whenever the number of the delivery holes being utilized changes in the forming machines, it becomes necessary to manipulate prior forming machines, whether of the reciprocating or rotary piston types, in two ways, namely,
1. pistons associated with inoperative delivery holes must be deactivated; and
2. a bottom plate must be mounted in the machine as required for each case.
While replacement of the bottom plate takes place essentially in the same way for reciprocating piston forming machines as for rotary piston ones, pistons are deactivated in different ways. With reciprocating piston forming machines which have their pistons in communications through rotary shut-off valves, ineffectual pistons are deactivated by inserting elements of cancellation of the piston movements in the form of combs or strips. In the instance of rotary piston forming machines, selected pistons are deactivated by matching apertures in the axial strips which are inserted through the machine rotor to act as continuous rotary pistons.
Although different in principle, the forming or casting methods of reciprocating piston and rotary piston machines share continuous supply of fluidized chocolate to all the piston chambers in the machine, and delivery of the fluidized chocolate to just those piston chambers which have their pistons activated at any one time.
The disadvantages of prior casting methods and machines are well known to the skilled ones, and no efforts have been spared to arrive at a solution, albeit a partial one, and improve the machines output rates while ensuring as accurate metering as feasible, to thus fill a generally felt need.
An accurate metering action is of the utmost importance for the output rate of chocolate forming machines, because many countries enforce strict specific regulations and because, owing to the very large daily output of such machines, even a few grams or fractions added to the nominal weight to meet tolerance requirements safely, may result by the end of a day in considerable amounts of a valuable product being wasted and unpaid for by the purchaser.
Listed briefly here below are the disadvantages and deficiencies of prior reciprocating piston forming machines both as regards their methods of operation and changing from one mold type to another.
Owing to the different time durations of the piston operation cycles, the pistons are subjected to differential wear rates; this results in less than satisfactory volumetric efficiencies of the various cylinder-piston units, because that efficiency would depend both on the chocolate viscosity and a tight seal and control of any play that might develop.
If such plays, or wear rates, reach a significant value, air may be drawn into the chocolate being drawn into the cylinder-piston units, and result in a much feared formation of air bubbles within the chocolate itself.
Deactivation of the ineffectual pistons requires that an appropriate comb be selected from those available and installed. In the event of a wrong selection of the comb, which cannot be entirely ruled out on account of this being a manual operation, considerable damage may be caused, such as breakage of the safety pins, or if the latter fail to break, breakage of the bottom plate and waste of both valuable product and time, or production losses. The very handling of such combs mat prove a difficult task with large size forming machines, which may have several hundred cylinder-piston units and involve, therefore, the use of combs of considerable size and weight.
A more frequently occurring error is that of deactivating one or some of the pistons. In that case, the backpressure due to the chocolate being delivered by the non-deactivated piston impacting on a solid area of the bottom plate is inadequate to operate the related safety pin(s) but is sufficient to cause local sagging of the plate which is already weakened by the various channels and holes formed therein. Thus, a gap is formed between the bottom surface of the grinder and bottom plate, wherethrough the chocolate would leak out and over the surface of the bottom plate in between the various receptacles to connect together adjoining receptacles with a film of chocolate. This results in heavier products and attendant economical loss for the producer, while it also adversely affects subsequent processing steps, such as shaking the articles out of the molds, packaging them, etc.
Within the forming machine itself, there occurs disuniform flowability, or viscosity, of the chocolate owing to the different temperatures of the piston units and during the chocolate drawing phase into the piston and valve conduits the fluidized chocolate flows into by gravity and remains there during all the time when the moulds are being used. On replacing the molds, the chocolate left there must be preliminarly removed by the operator and aggravates downtime.
Pressure irregularities within the forming machine, and consequently, possible uneveness of metering.
Considerable overall time expended to perform the various manual operations for switching from one mold type to another.
Rotary piston forming machines have on the other hand the following drawbacks.
Time requirements for replacing a strip forming the rotary pistons with any other strip, as the occasion may dictate.
Presence in the continuous deactivated chambers of a mass of inactive chocolate and, as a consequence, pressure differentials between the pressures in the delivering chambers and the deactivated ones, with attendant risk of chocolate leaking from the activated chambers into the deactivated ones, and again, of uneven metering.
Owing to the residence of chocolate inside the deactivated chambers, viscosity differentials may occur and propagate into the common mixing chamber, and hence into the metering chambers.
As regards replacement of the distributor bottom plates, this is carried out in the same manner for both forming machine types.